#include <iostream>
using namespace std;
const int N = 1e5 + 5;
const int MAX_BITS = 30;
const int root = 0;
int trie[N * 31][2], idx = 1;
int nownum[32], nowp, ans;
void entrie(int x)
{
    int i = MAX_BITS, p = root;
    while (i >= 0)
    {
        int a = (x >> i) & 1;
        if (!trie[p][a])
            trie[p][a] = idx++;
        p = trie[p][a];
        i--;
    }
}
void getans(){
    int res = 0,p=root;
    for (int i = 0; i < nowp;i++){
        int a = trie[p][0], b = trie[p][1];
        if(nownum[i]&&a){
            res += 1 << (MAX_BITS - i);
            p = a;
        }else if(!nownum[i]&&b){
            res += 1 << (MAX_BITS - i);
            p = b;
        }else
            p = max(a, b);
    }
    ans = max(ans, res);
}
void dfs(int p)
{
    if (nowp==31)
    {
        getans();
        return;
    }
    int a = trie[p][0], b = trie[p][1];
    if (a)
    {
        nownum[nowp++] = 0;
        dfs(a);
        nowp--;
    }
    if (b)
    {
        nownum[nowp++] = 1;
        dfs(b);
        nowp--;
    }
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    cin >> n;
    while (n--)
    {
        cin >> m;
        entrie(m);
    }
    dfs(root);
    cout << ans;
    return 0;
}